Sealant Application

Sealant Application

Backer Rod smaller1. Sealant Backing

  • Choose the appropriate sealant backing based on the available joint depth. Sealant backing will prevent three-sided adhesion, control sealant depth, and allow for tooling to ensure proper sealant / substrate contact.
  • Foam cylindrical backer rod is typically installed and should be approximately 25% larger than the width of the joint to ensure a tight compressed fit.  Three types are currently available: open cell, closed cell and hybrid.  Consult the sealant manufacturer for the recommended backer rod type
  • In joints where depth is not adequate to acept a backer road, a polyethylene bond breaker tape should be installed.

Refer to Pecora Technical Bulletin #106 Backer Rod Use for more information.

2. Sealant Mixing (multi-component sealants only)

    • If a sealant requires mixing in the field, ensure that the  manufacturer’s published mixing procedures are strictly followed.
  • Thorough and uniform mixing is vital when installing multi-component sealants.  Be sure to utilize the correct mixing equipment as recommended by the sealant manufacturer.

Fully Mixed Sealant smaller     Sealant mixing in process smaller

3. Sealant Dimensions

  • The correct sealant dimensions are critical when installing joint sealants and will ensure the sealant maintains its designed performance characteristics.
  • Width of joint to depth of sealant should be two to one (2:1) with no joint depth being less than ¼”.

Width to Depth Ratios smaller

4.  Sealant Installation

  • All sealing should be done when temperatures are above 40°F.  Preferably, sealants should be installed at a median temperature and not at temperature extremes (low and high).  

Refer to Pecora Technical Bulletin #65   Caulking at Low Temperatures for more information. 

  • All surfaces receiving sealant should be DRY and CLEAN.
  • Sealant should be applied in a continuous operation using a professional grade cartridge-type caulking gun or bulk loading gun.
  • Joints should be filled uniformly to the required sealant depth.  Sealants may be recessed if required by manufacturer.

5.  Tooling of Sealant

  • Hourglass Sealant Configuration smaller 2Tool the sealant with light pressure to spread the material against the sealant backing and joint surfaces. Use a tool with a rounded tip to keep a concave sealant profile in the joint and maintain the industry standard “hourglass” configuration.
  • The sealant should be dry tooled unless the sealant manufacturer specifically approves otherwise. If approved, the tool may be dampened with a sealant manufacturer approved tooling agent (typically mineral spirits).
  • Do not use water or soapy water as a tooling agent.  Avoid over tooling.
  • Tool the sealant at window sills and similar places so that precipitation, cleaning solutions, etc. will not pond.
  • Any masking materials used are to be removed immediately after tooling while the sealant is still in its uncured state (wet).

NOTE:  All remedial sealant installations should be verified for proper performance through field adhesion testing.  

Refer to Pecora Technical Bulletin #55  Field Adhesion Test Methods and Test Log for more information.

Refer to Pecora Technical Bulletin #108   Sealant Application Guide for additional application information.

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